<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
</head>
<style>
    div{
        width: 200px;
        height: 1000px;
        background-color: red;
        margin: 0 auto;
    }
</style>
<script src="lib/jquery/jquery.js"></script>
<body>
    <div class=""></div>
</body>
<script>
    $(window).scroll(function () {
        var a=$(window).scrollTop();
        var b=$(window).height()
        console.log($(document).height());
    })
</script>
</html>